Diagnosis and treatment of multidrug-resistant tuberculosis

Multidrug-resistant tuberculosis (MDR-TB) is a great public health concern worldwide. MDR-TB denotes bacillary resistance to at least isoniazid and rifampicin. Extensively drug-resistant tuberculosis (XDR-TB) is MDR-TB with additional bacillary resistance to any fluoroquinolone and at least one second-line injectable drug. The treatment of MDR-TB requires prolonged administration of a toxic second line anti-tuberculosis drug and generally has poor outcomes. XDR-TB requires more complex treatment and has higher mortality. MDR- and XDR-TB arise because of inadequate or interrupted administration of first-line treatment and can be transmitted in the community. Thus, prevention of the emergence of resistance is the first principle in the management of MDR/XDR-TB. To prevent the emergence of drug resistance and transmission of MDR/XDR-TB, the adequate prescription of an anti-TB drug by a physician and good adherence of patients are essential. In addition, rapid diagnosis of drug resistance using molecular tests such as a line probe assay and Xpert MTB/RIF and the programmatic management of MDR/XDR-TB by designing an effective regimen using available drugs (a newer generation of fluoroquinolone, second-line injectable drugs, second-line oral drugs, and pyrazinamide) based on a guideline are an important strategy for controlling MDR/XDR TB. Despite the long duration of treatment, the treatment success rate of MDR-TB for patients who started treatment in 2009 has been 48% according to the World Health Organization. Thus, to improve the treatment outcomes of MDR/XDR-TB, new drug development is necessary.